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Full text of "Nuclear Physics by Enrico Fermi: Appendix and Index"

Oh. X 2J5 Appendix: DISOUSSIOK OF FIG. X.g, p. 221 To get from the experimental counting rates given by the left-hand scale to the absolute production rates given by the right-hand one, the counter is calibrated in a pile where "nv" is known ( "nV" is what we v.-ould call a flux if we were dealing with a beam rather than with isotropic velocities). If we regie ct the high^nergy collimated neutrons in the atmosphere (an assump- tion which might be justified for x » 57 fifo*) w can then call the atmo- spheric neutron velocities isotropic, so that the calibration is justified. Once we know nV we can calculate the rate of neutron absorption per gram of air, and we can certainly replace "abeorbed" by "produced" since there is an equilibrium condition. it might be heartening to point out that the order. pf magnitude of these production rates can be predicted by elementary considerations, starting from the proton intensity given in Fig. X.6, p. 222. We shall have to make three arbitrary assumptions: 1, For x > 57 g/cm 2 the density of neutrons and protons is very roughly the same. (At these depths moat nucleons are secondaries, and the number of secondary neutrons and protons should not be too different.) 2 A neutron is "absorbed" as soon as it hits its first "air" nucleus- 5. It hits an air nucleus after travelling 57 &/cm 2 , i.e. after a distance L = 57/^ am (fi is the density of air). Also remember the assumptions of the calibration: a. Isotropic velocities, b. Equilibrium. V.'iih these assumptions the production rate = the collision rate 5 Rj ■v-V -1 _=j X.20 collisions sec cm '? where V is the average velocity, L is the mean free path. All that remains is to state nV in terms of I ; : , and this may be done vert . ' almost immediately from the sketch. The number of particles effusing normally through the unit-area hole in the box is, by definition, dK - I , dt dw vert. but, as discussed in every book on kinetic theory, it should follow from the sketch that i/V- Xji~>{it dN nV tS dt 7^ 4-7T 4tTI 'vert . 41TX Thus X.20 becomes ■ ytrt . -1 -* collisions sec cm > L S7 7? However the croduction rate of Fig. X. 5 is expressed per gram rather than per cm?, so our expression must still be divided by p. The -'« ™- ™* we have r - 4tT I vt ^t, 57 p ' s cancel, and collisions sec * g 2 ?6 Appendix (continued.) Ch. X. If £rm Fig. X.6, p. 222, we pick a value such as I v = rt = 5 x 10" 2 at R 1 i — I'D"? at x: 400 §/»« 400, we find Compariaon with Pig. X.J, p. 221, ahowo that the agreement, f ortuitoualy, is quite good. REFERENCES FOR COSMIC RAYS 1. Montgomery, D.J.X., "Cosmic Ray Physics," 1949 2. Janossy, L. , "Cosmic Rays," 1948 3. Rossi. D., "Interpretation of Cosmic Ray Phenomena," Rev, Mod. Phys. 20, 537 ('48). 4. Helsenberg, W,, "Cosmic Radiation," 1943 5. Cosmic Ray Symposium, Rev. Mod. Phys. 21, ('49) 6. Jauch, J.M., "Cosmic Rays," Tiucleoni cs 4, (Apr and May '49) 7. Tiomno and Wheeler, "Guide to the Literature of Elementary Particle Physics, Including Cosmic Rays," American Scien- tist 37 (Apr. and July '49) Also bound separately. H. Papers delivered alt the International Conference on Cosmic Rays, CnaaO) Italy; Sept. 1949 (to be published) 9. Symposium of the Inter university Cosmic Ray Laboratories, Echo Lake, June 1949. (To be published early in 1950 by the U.S. Government Printing Office.) PROBLEMS 1, If you were travelling in an interplanetary space snip, what sort of apparatus would you need to measure the total Inten- sity of cosmic rays? 2. Assume that your laboratory is at tiie top of the atmosphere. Design an experiment to set an upper limit on the intensity of urimary electrons m cosmic rays. 3, Plot the semi-vertex angle of t'l function of p at A = 50°. g] Lowed ;ones ( K) Some notes addsd Sap. 1950, and July I951 NOTES OK MESON TABLE, P. 153 237 neutral ^arMclL^ ** ^ lst °- Thar9 >W b«n reporta of charged and "find But" f L^ flo 8; 5 w (i) .i^iS'v- L erhap : 220Qm ' Sea Rochse - Anderson. Fhys Hev 78 2W f4l- » T t ' ^**' risia °' Oowan - Md ' y Be/ ' -gr',Z°^ 5 °J' Armenteros, Barker, Butler, Cachon, Emd Chapman, Nature 167 . 501 ('51), — S £ BV - ° ^» -LUj I pij. The maea of the n° is diacuaaed below. , - ^»- -" 9V - g^ i m { Pl). The mean life of the v" ia dlacuesed below. THE NEUTRAL tf-MSSON 4' 1 ',T r 3 l 51 >' and a r^Iew of experimentiper-fbrmad inside +fc« vacuum tank, by Oardner et al . , Science HI . 191 (150). ^ th ° ^ Next we Mention briefly three experiments which indicate the existence of a -FT which decays into two gammas, probably in less than 10-13 sac. *** V? Bt ' ■* haVS been obBerved *° c °oa from various targets when bombarded with high-energy protons*. These A have a production crosa-section whoee dependence upon proton energy i a much like that of charged pi on cross-sect Ions. The ^-energy ia roughly 70 Mev on the average (half of the energy of a TT± ) ana their energy spread is in agreement with the floppier shift due to the ve lOClLV Of* t.ho Tlfl rflrrr. maarvna t -P+ =>-- ^^n*,l„4 j. i_ . fJ . ~ , , locity of the parent me eons fT"s "' ' Cou*,l After examining the position of the shadow of a lead screen (see the schematic sketch) and calculating the distances traveled by the n ! s before they decay (allowing for the re lati viatic time dilatation}, the experi- menters have been able to state that the mean life of the ti° ' s is < 10"" sec. In this time the pi on travels only a few mm. -14 The upper limit on this mean life ha a been reduced to 5 X ISS"" <-.-. :j-., examining (indirectly) the point of origin of gammas produced by the decay of n 8 produced ia coamic ray stars, observed in emulsions****. These gammas create electron pair a, and the bisector of the angle between the two tracks star ****** thS 9tar ' " lB fOWld t0 pasB V9r ^ c - loae t0 the 7n „ fMffC 1 , a ■ . ., In a second experiment, 7 ! s of about I a i^T = MeV C?)) of nuclear origin ^ve been observed during the bom- bardment of nuclei by 350 Mev x-rays from the Berkeley synchrotron**. Coinci- dence and angular correlation meaaurementa show that these /' s are emitted in pairs, moat probably from particles traveling with speeds up to about 0.3c, This speed ia calculated" by considering the aberration of two 5" s emitted by a relativxstic particle: aeen from the rest system of the emitter, the two Photons must leave in opposite directions, but seen from the lab, they must come off in a forward cone, ' ' Apparently the reaction is / + ft — v N 4 TT where N stands for a Nucleon. rr' mzli*$ % y ♦Bjorklund, Crandall, Moyer, and York, Phys. Rev. 77 . 21? ( l 50). **3teinberger, Panofeky, and ataller, Fhya. Rev. 78. 802 ( l 50) , **!*» H asetumsd that th9 reader ha a already read the footnote, p, "••Carlson, Hoopsr, and King, Phil. Mag. 41. 701 ("50) 221a 2?8 HEW DEVELOPMENTS A a an example, suppose thai a J00 Mev photon is absorbed by a Maclean and thai one Tr°of rest mass 135 Mev is created. Moreover, consider the special case in the chq system where the pi on comes off forward, while the nude on flies back. In this case the reader can easily check that in the lab the nucleon has only about | Mev kinetic energy, leaving the pi on with kinetic 9nergy slighly greater than its rest mass. Now it is trivial to show that a particle with KE = Mc 2 has a speed of 0.866c. Thus the /-emitters, deter- mined by the aberration measurements to have speeds up to about 0.8c, are probably TT*' s . It has been shown* that an isolated IT with, spin ft or 1 cannot decay into two /'a. Unless one wants to include the possibility cf spin t 1, it looks as if a TT° has snin 0. Since the data seen to show a fair amount cf similarity between charged and neutral oions, there may even be tentative indications thai- all pious have spin 0. 13 A third experiment which indicates the mass of the 1T consists in allowing ir"'s (made in the Berkeley cyclotron) to co.te to rest in a tank, of high-pressure hydrogen**. We have already discussed on p. 13J the capture into Bohr orbit a of mesons hy a nucleus. A pi on which is in a state of low angular momentum will probably interact with the nucleus within the 10" J sec mean life cf the oicn. In case the nucleus is nothing but a single proton, the result is not a star, but probably one of the two following reactions P-+fT** -* X(9 Mev) * f (1J2 Mev) or P +■ Tf -* N(almost at rest) + tf (few Mev) 1 followed by it" -r 2-V (each of —65 Mev). ' Both cf these processes seem to occur. The tr" 1 b are created inside the cyclotron where it is hard to run elec- tronic counting equipment, so it has not been possible to determine the speed of the IT* 'a by measuring the angular correlation of the coincident / ' s , but one can still examine the Doppler effect, looking at the 7' s with a pair elec- trometer***. 7rom this Doppler data it is claimed that 1.3 Mev < (M^ , - MjjoJ^ 1 < 4.7 Kev. SCINTILLATION COUNTERS It has not been mentioned in thie book that when charged particles (and also- in particular- when 7" s) pass through many materials {solids, liquids, and gases) these materials may give off visible light. The light may tnen be detected with a photomultiplier tube. This is the principle cf the scintil- lation counter, which is becoming of increasing Importance. These counters can be made with pulse widths a a little as 10 ~9 aec, and have other characte- ristic advantages: their response depends fairly linearly upon the energy which the scintillator absorbs, so that they may be used ae spectrographs****,' they are sensitive,- and a scintillating crystal does not have to be surrounded with 3ome more or less transparent envelope, as do other counters. For review articles see "Fluoreaeenceof Liquids under /-Bombardment^' Kallman and Pu'rst, Nucleonics 7 . &9 (July 195°); ^ n< ^ a review by 3ell and Jordan, Nucleonics . 5, ?0 (Oct. 194?). *Yang, Fhys. Rev. 77 . 243 ( ' 50) **Panofsky, Aamodt, and fork, Phvs. Rev . ~(9 , 825 ('50) ***i.e. one converts some of the gammas to pairs in a thin foil, measures the total energy of the pair by determining the electron orbits in a magnetic field, using counters in coincidence. ****Bell and Cassidy, Phys. Rev. 79 , 173 ('5°); Hofstader and Mclntyre, Phys. Rev. 79, 369 ('50) HEW DEVELOPMENTS 259 COSMIC RAYS: Fluctuations with Time Diurnal Effect. For a discussion of this daily- variation in intensity see Elllot an <i Do Iter, Pro_c. Roy. ggs. Lond A65, 157, ('JO). Solar Effect. These variations follow solar activity (solar f ] areg to L^T^^T' etC - } * Sae Forb « sh > Stinchcombe, and Schein, Phys. Rev. 19, 501 ('50); Adams, Phil. Mag. .. 4l_, 50* (' 5 0); Simpson, Phyft, Kevf$l, 895 GENERAL ^jMM MM Bgj TJTTCLEAE PFY.STnR Bethe, HA. et al. "Wuclear Physics" Reveled. Fhys. 8, 82 (1956) 9 69 and 245 (1957). Referred to in this book as BotheT, B, and C. ' Bethe, H.A Elementary Nuclear Theory," Wiley, 1947; called Bethe D. fermi, E. Elementary Particles , " Yale Fress, 1951. Friach, 0. "Progress in Ivuclear Physics, 1" Academic Press, I950 . Gamow, Gf. , and C. Critchfield "Theory of Atomic Wucleus and Wuclear Ener.v bources, " Oxford, 19^9. Goodman, C. "Science and Engineering of Wuclear Power;' Addison-tfesley 1947 Heitler, W. Quantum Theory of Radiatior" Oxford 1944 ... LA 255 (AEGD 2664); Ferni, E. , "Houtr on Physics" ^^menta^'lSr'' ^ " (Matlonal EureaU ° f Standard), Superintendent of Docu- Rasetti, E. "Elements of Nuclear Physios" Prentice -Ha 11 I936 Hosenfeld, L., "Wuclear Forces" Intsrscience 1948. Schiff, L.I. "Quantum Mechanics" MaGraw-Kill 1949. More specialised references are found at the end of the individual carters, ana an the footnotes. ' The following bibliographies may also prove useful: Beyer, R.T. "Foundations of Nuclear Physics" Dover 1949 Tiormc and Wheeler, "Guide to the Literature of Electa ry Particle Phvsics Including Cosmic Rays" Am . Scientist . 57j 2C2 (1949); also bound' separately . For biological applications, instruments, see Siri, W.E. "Isotopic Tracers and Wuclear Radiations" McGraw-Hill 1949 (one of the Hticlear Energy Series). Note added Feb., Lggj Some of the Sajor developments sir.ee the writing of these Hates ars covered in the following books : Marshall , 3 . S . "He 3 o n %s W MofiESW Kill, 1952 Thorndike, Ala- Mesons - A Sugary of Experimental Fact" McGraw Mill, 1<??2. LePr knee Ringuet, L. "Cosmic Ra/s" Prentice-Hal"! , 15^0 Rossi, Bruno "High-Energy Particles" Prentice-Hall, 1052 S'J^tt ^•;'; rOSr93S ^ C °^ Raj P ^ 31CS " A ^ « the Co B eo- nag en Confer ence*l Innersoience, 1952. The ideas of cnarge- independence (isobopic spin) and fcheir apol^tio ns to mesons and to light nuclei are discussed by M. Geil^ann and a HilSbrSd m a for .nooning issue of the American Journal of Phys ics, " ' flgn M ^( ' lew developments are covered in tw, voltes of notes by R.P. Fevrma, (l9:,l-,2) available from California Institute of Technology, Pasadena! ITIT. Reference should also be made to a very complete new text dessrinfrts Ui5±cs D J J - M - Slatu and >/.F. Weisskopf, Vfiley, 19^2. 240 DOTATION The following list gives most o that are quite standard are not list special meaning in only one chapter, it a symbol has a .meaning that needs number following it gives the place nition is found. Numerical values f the symbols used. Symbols ed. Where a symbol has a the chapter number is stated. fuller explanation, the page in the text where the def i- are on p . 240 . ft- Bohr radius, 5.S9 x 10 cm a a- Singlet ana triplet scatter- * ing length, VI and IX arrni Atomic mass unit, = Mj_ A Atomic mass number, N n Z A Vector potential b Collision parameter, 27 ,ZZS BE Binding energy D e E e f(0 i % i x i ;-. ". Q N N P S 0. Q VI and IX, coeff. of tth partial wave, 117 IX, thickness electronic charge = -4.805 x lO' 1 " esu , e e , etc., unit vectors Energy eigenvalue, T + IT Electric field strength,-?^ ) Angular dependence of wave Total angular momentum of atom, I + J Coupling constant, Ecrmi constant h/2tT Magnetic Eield Total nuclear ang. momentum Intensity, erg cm^sec " l II, average ionization potential, 30 Total ang. momentum of extra-nuclear atom Propagation constant, 2rr/2 Radiation length, 49 Mean free path for pair production, 49 REST mass of electron Rest mass of a particle Index of refraction a Neutron g Atoms or nuclei per cm II, electrons cnT 3 , 28 Magnetic ri&idity, (pc/2e)=#/> ,£) or q(r,rj, IX, slowing ' down density, 187 IX, rate of production of neutrons 1 , 184 Energy of reaction, exo- thermic QUadrupole moment Radius of electron and of proton X, radius of earth Ry s S T U IT V Vv' x 7: r r e & K I A K A A /* r or <r(e) <r <r *? Radius of potential well. Range R3 r dberg energy, -13.52 ev jspin angular momentum Kinetic energy, half-lif e, temperature . Potential energy Till i velocity Velocity Total relativistic energy, 5 Atmospheric depth, g can*, 215 Charge of particle in units Of ^--electfoniG cViarge. Charge of incident particle II, h^/ic'' , energy parameter VI 1> lPfi VJ - J t,V ' ■ tJ V/c phase shift of -tth partial wave , I - (t+) '* X, angle between T and west, 2 25 Till, energy width of reso- nance at f max. , 154 IX, In neutron energy IX, neutron scattering angle in lab . S7fstem, 182 Total scattering angle, 36 Range of meson field, 135 Mean free path, 184 Radioactive decay const, 1 X, magnetic latitude, 225 Cornpton wavelength/2-rr IX, absorption mean free path, 184 reduced mass Nuclear magneton Magnetic moment V , hv/mc^ IX, reduction In In (neutron energy) per collision, 183 Pauli spin operator, 112 Differential cross section Total cross section Klein-Nishina scattering cross sectlon( Cornpton), 41 II, o~ for photoelectric effect II, Thomson cross section 141 % II, Thickness in g/em^ t Mean life T£) IX, neutron "age" to angular frequency, solid angle fl Volume of nox for normalization Denotes exeited nucleus Order of magn: Approximately ■ *** Order of magnitude r a = #% e 2 £42 TABLE OF PHYSICAL CONSTANTS General Physical Constants : 0,529 x 10 ■ cm. Bohr Re din a e^/yic «= 1/157-05 Fine structure constant J?e £s l_ in x 10 cm/sec. Velocity of light x ip""*0 eau = 1.602 x 10" emu. Electronic charge D~^" e cm^/sec . Fermi constant in "bets decay, p. 10 ' erg-sec. Planck constant , x 10 ' erg-sec. l.Jfl x lO - !" erg/degree. Boltzmann constant 6.025 x 10 5 /mole. Avogadro's number 2.82 x 10 * cm. Classical electron radius c oc = c = a = g «6 h = H = k «a 2.988 4.805 2.5 x 6.624 1.054 'a -li ^ = #/mc = 5.86 x 10~ iJ - cm. Compton wavelength/2'Tr' Deutoron: n-p scattering tf «= 20 , J Triplet state t (p. 115) BE = 2.25 Mev = 5.58 x 10 U, = -21.0 Mev, Veil depth Tq = 2.82 x 10 -1 ? cm barna -6 erg n-p triplet scattering C^=4.4 barna a j = 0,59 x 10~ 12 cm Wave fen phase at edge of well: 108 Singlet state: (p. 120) U 1 = -11.5 Mev, Well depth n-p singlet scattering a, = 68 barns a,= -2.52 x 10~ 12 cm , Quadrupole moment Q,- D = 0.00275 x 10" lP« 15) Magnetic Moments; ■^Bohr = 0-9 2 7 5 x 10" 20 erg/gauss /'nuclear -■ 5- oi * * 10 erg/gauss = l/185^ Bohr /*electron = -1-002 >" BDhr /"proton =^2.7896 >^ cIeGr /"neutron — -l.ylOp yW nuc x ea r /^deuteron~ ^*°5647yW nuc ^ eBr Ma s se s : (see p. 2; mass formula, p. 7) % - Mp = Ma- m = M ir + 1 amu = 1.660J x 10~^ 4 g = 951 Mev 1.00759 amu 1.00898 amu 1/18J7-561 M H = 9.1066 x 10 d ° g= 0.51 = l40.8 Mev = 276±6 electron masses =158 Mav = 107 ■ Mev z 270 electron masses 210-4 electron masses Nuclear Spins: electron if neutron i- proton J deute triti Li° Li 7 Be 9 B !o B 11 »ron 1 .um.H? jg 1 5/ 2 V 2 5 3/2 Mev. Maas of electron 243 Miscellaneous Constants, in Alphabet! cai Order; Curie = J.71 x 1Q 10 disintegrations/as c Dose (see p. 18) e.v. = 1.6 ^ lCr iei erg e.v. = 8100 etc -1 for photon e.v. = 11,600° Aba. (setting 1 e.v. *= fcTJ k. propagation constant for electron = \jlp ^ E . ,„ el ^s) s= c.5i*iO \l j)sE m ev) k , pr o c a ga t i on c o net a at for pt'ot on = JSM)s/ k .E »« e»^l = 3- 1 2 * i », ('<E. m e.Y) J" ^radiation length (p. 4?) ^ - 550 e iti NTF Air _ 9.7 cm in aluminum .517 of. in leas 9 a — mean free -ath for cair production (p. ^9) L.. ■ = 57 g/'em 2 . Geometrical collision length for air nuclei (p. 220) Usv = 1.601 x 10" 6 erg j, R , = 1.5 x ICT 1 ? A 3 (p. 6) r™ roentgen e that X-ray doss *hich, passing through STP air, leave a ' 83 ergs/g, or liberates 1 esu of positive ions per cn^ Rydberg: R = 1J-52 e.Y.- 3 Rhc R = 109,737 cm" 1 , Rydberg constant for infinite mass T (half-life, gaama decay, p. 96) „. . _ Velocity of thermal neutron = 2.7^ > 10^ cm/sec (thermal ss J00 Ahs.)^ ^ Velocity of thermal electron- 1 .117 x 10° cm/sec J £ x =1050 g/ra 2 , depth of standard atmosphere at sea level Year = 3-16 * 10? secends Athei ,-8 (thermal = 300° Abe.) thermal neutron l'°l x J.U ^ =^1234o/electron volta) in Angst r oris, for photon p: ±r = 1.225 xlO-3 g/cm 2 ^Thcm^son^" 66 * 10 ~ 2 ^ „ . nQ ,s X ( mean life; radioactive families, p. 17; ga^a aecay, p.ybj J INDEX Abraham, M. , 4l , 44, 46, ?4 Absorption coeff iciente, 59 — th.iclcri.egs for cosmic rays, 220 Accelerator, betatron., 23 —Co ckroft-Wa.lt on, 24 — Cyclotron, 24 Adiabatic invar iance , 29 Allen, J. 3., 84 Allowed, regions (go ami rays), 227 — cones " " 229 Alpha-particles, Oh. Ill, 55-69 — lifetimes, 58 — long range, 6j — 3emi -classical theory, 58 — 3peotra of. 66 — virtual level theory. 59 Alpha-alpha scattering, l49 Angular correlation, j»..-*> , 85 Angular momentum, total, 11 — electronic, 10 — nuclear, 10 — nuclear models, 169 — isomers, 106 — selection rules, 96 see also "spin 11 . Anti-neutrino, 85, 86 Argonne graphite pile, 21J Artificial production of if' s, 1% Atmospheric data, 215 —depth, 215 Atomic mass, physical scale and chemical scale, 2 — masa formula, 6 Auger electrons, 101, l4l Avogadro's number, 2, 240 Axial vector, 99 BARRIERS, arbitrary, 56 — coulomb, 57) 58 — rectangular, 55 --factor in nuclear reactions, l42 163 Bartlett force, 112 Backs r, S, 4l, 44, 46, 54 Be , 149, energy diagram, 151 Eerkeley cyclotron — deuteron beams, 177> 178 — neutron beams, 121 — jT- mesons, 131 Beta-decay, Oh. IV, 69-87 --theory, 72 --spectra, 76. 78 — rate, 76 — and gamma-decay, 89, 105 Betatron, 2J Bethe, 8. , 257 , 30 , 31 , 32, p4 Beyer , 257 ■ Binding energy, J. 2 Block, $1 Bohr, 27, l48, 166 -- formula, 27 --orbits for ,> -me sons, 13J Breit-wigner formula, 152, 157 Bremsatrahlung, 4j Br S °, 106 Bursts, 219 C^ in atmosphere, 22Q CAKEOH, gamma absorption resonance, 175 Cerenkov radiation, 32 Chadwick, J., 54, 54 Chain reactions, 208-215 Chemical binding effect on neutron scattering, 194 Coherent scattering, 196-203 Cold neutrons, 180, 199, 203 Collision thickness in air, 22P Commutation relations for I, 16 Compound nucleus, l47 Compton effect. 58, 40 — wavelength, 41 , 240 Conservation of energy, 69, — in meson theory, 136 Constants, physical, 240 Conversion, internal, 101 Cu, gamma absorption resonance, 175 Coryell, 32 Uosmic Rays, Ch. X., 215-235 — absorption thickness, 22.o — allowed cones, 229 — allowed regions, 227 — bursts. 219 — collision thickness, 22o — east-west assymetry, 243 — electronic component, 2213,222 — forbidden regions, 257 — hard component, 221b — intensity, 215, 222 — latitude effect, 235 — Liouville theorem, 2J2 — mesons in, 221,3,222 —motion of, in earth's field, 225 Jn sun 1 s field, 215 — N-component, 217, 222 — primary, 215, 233 — protons in primary radiation, 216. — references, 237 — secondary radiation, 217, 22J — shadow effect, 232 — showers, 49 219 — soft component, 221 jp 223 — stars, 217 — trajectory of, 225 Coulomb scattering, 125-127 Crane, H.R. , 84 Cross section for nuclear reactions, 141, 143 844 HB Ccckroft-Walton accelerator, 24 Curie, 18, 240 Cyclotron, 23 (also sag Berkeley) DECAY CONSTANT, A , 1 £ -functions, 106 ; rays , 2i9 Density of nuclear levels, 158, 161 Density of states in a box, ~J6 Detailed balance, 145 Deuteron, 113-121, 169 — nuclear potential, 115, 116 —stripping, 177 — virtual state, 120, 121, 175, 199 — wave function, 115-116 Diffraction of neutrons, 200-201 Diffusion theory (neutrons), 187-194 — length (neutrons), 1J>J Dipole (aee Electric, Magnetic ...) Dirac theory of the electron, 48 Disintegration of jy' a, jn 1 s, 152,22-1 a Double j3 -decay, 86 EAST -WEST ASSYKETRY, 233 Einstein mase energy relation, 2 Elastic scattering of neutrona 181 -18? Electric Dipole, 92 — abaorption at high energy, 100 — emission, 94. 96, 106 — static moment forbidden, 15 — radiation forbidden, 99 Electric quadrupole, 93 — emission, 100, 108 Electrons, existence in nucleus, 75 — negative energy, 71 Electronic component of cosmic rays, 22U, 222 Ellis, J4, 54 Endothermic reactions, l4l, l44 Energy- diagrams, beta decay, 70 — Be° (compound nucleus), 151 — isomeric states, 106 Entropy of nucleus, l6l Equilibrium, radioactive, secular, 17 Evaporation from nucleus, 162 Exchange forces — experimental evidence, 121-123,178 — mesons, lj4 — saturation, 113 — types, 112 Exothermic reactions, l4l, 144 FEATHER rule, 32 Fermi, g . , ionization lose, 32 paper on pile theory, 208-213 Fermi age equation, 187-188 Fireman, 87 Fission, 164-208 — asymmetry in, I65 — in chain reactions, 208 — delayed neutrons, I67 — fragments, 166, 167 — neutrons emitted, I67 — stability against, 164 — triple, 167 Forbidden cones and regions, 228 — transitions, 100 — strictly forbidden transitions, 104 Form factor, 200-201 Fourier analysis of J, 107-109 F?r Tables, 82 Fur ry, 87 GAMMA RADIATION, Ch. V,, 89-106 — energy of, 89 —half-life, 96 — multipole expansion, 92 Gamcw , G. , 55 Gamow-Teller selection rule, 81 Gamow factor , 58 Gas model of nucleus, 159 Geometric nuclear a- , 22.0 Geiger-Nuttall law, 66 Glendenin, 32 "Golden Rule # l n 136, 148 "Golden Rule # 2" 142 G-oldberger, 177 Goldhaber, 175 Goodman , 237 Graphite filters, 203 Greisen, K. , 36, 4p, 54 Gyro magnetic ratio, anomalous, 20 HALF LIFE, defined, 1 — alpha radiation, 58 — beta " , 82 — gamma " , ^6 Hamilton, &5 Hard component of cosmic raya, 221b, 22.2 Hayakawa, 221 Heat of condensation, 4 — of condensation, 7 Heisenberg, W,, I37 —force, 112 Heitler,240 , 39, 4i , 45, 47, 48, 50, 54 He X 169 He 5, 169 High-energy scattering 121, 122 Hydrogen, ortho- and/para-, 199-200 H 5 , 169 Index of refraction for neutrona, 201-202 In 11 ?, 106 Induced emiasion, 95 Induction, nuclear magnetic, 15 Inghram, 87 Internal conversion, 101-105 — coefficient, 101 103 245 Internal conversion (cont.) — experimental, 104-105 — relativistic treatment, 104 — selection rules, 104, 105 — theory, 101 Intensity of primary cosmic rays,21C " ' ■ secondary " " ,222 Inverse processes, l45 11 , beta-decay, 85 Ionization of a gas, 33 — chamber, 33 — loss by heavy particles, 27 — electrons, JO — — mesons Isobar, defined, 1 — behavior of, 8 — stability of, 71 Isomerism, 106 Isotone, defined, 1 jamossy, 257, 57, 53, 5^, i?7 K-CAPTURE, 70, 71, 84 K-conversion, 101 Kennard, B.H., kl Klein-Gordon equation, 134 Klein-Niehina formula, 4l — plotted, 42 Konopinski, 81 Korff, S.A., 53 Kurie plot, 80 LA 24 and 255 , 237 Lagrangian, relatlvistic electro- dynamic, 226 Larmor's theorem, 15 Latitude effect, 233 Lattes, 131 Lead, absorption of photons in, ^0 Lifetimes (see Half Lives) Lindsay, 55, 37 Liquid Drop model, y — applied to fission, 164 Li 6 , 170 Livingston, M.S., 237, 31 , 54 Low energy scattering, 194-195 — cross section, 119 , 120 MAGIC NUMBERS, 170 Magnetic Dipole, defined, 93 —emission, 95, 100, 109 Magnetic Moment, nuclaons, 13 — deutaron, 13, 171 ——earth, 228 ~3Un, 215 Magnetic rigidity, 225 Magneton, Bohr and Ku clear, 1J Majorana, 86 —force, 112 Mass (amu) , 2 Maes, atosic mass formula, 6 — defect, 2 — number, 2 — reduced, 5 — relativistic, 4 — of mesons, 153 Matrix element, in beta-decay, 75, 81 — in gamma-decay, 92-96 Mattauch, 257 Mayer, M. 3. , 87 Mean free path for neutrons, 185-6, 189 32! Mean life (Half life) Meson, decay of tT and p, 132 — heavy, 135 — in cosmic rays, 220 — Tfand u, p and <r, 151-2 —neutral, 155, 221 — pseudo-scalar, vector, tensor, 135 —theory, 1% 23, 135-7 Minimum ionization, 131, 3 3 Mirror elements, 83 Mn, (n,n.) resonance, I56 Model, liquid drop, 5 — orbit, I67 — statistical gas, 159 Moment (see Magnetic, Electric, etc.) Morrish, 84 Mott, 50 p-Jfeson, 151, 230, 223 (muon) Multipole expansion, 92 N-QOMP0NENT, 21? , 222 Negative energy levels, 48 Neutral meson, 1J1, 221b Neutrino, 69, 84-7 — antineutrino, 85 — flux from 3un, 85 —mass of, 79, 84 —virtual , 87 Neutron, age equation, 187-8 — beams from Berkeley cyclotron, 122 — capture in light nuclei, 174 —crystalline diffraction, 200-202 — decay of, 70 — density in atmosphere, 220 — diffusion theory, 187-94 — elastic scattering, 181 -85 — graphite filter, 203 — in cosmic rays, 22o — index of refraction, 201-2 — interference cf, 196-205 — macrocrystalline scattering, 205 — nascent, 191 — neutron-neutron forces, 129 — neutron-proton forces, 113-23- potentials, 122-3 scattering, 117-20 — polarization, 204-07 — ecattering in ortho-andpara-hy-irosen, 199-200 — slowing down, 181— S3 £46 : ,W& Neutron sources, 179-81 —thermal, 4, 191-4 Notation defined Nuclear forces, Ch. VI, 111-29 — non-central , 115-4 — spin- dependent , 114-5 Nuclear reactions, l44-5 — listed individually under Reactions Nuclear shells, 150, 167, ORBIT model of nucleus, 150, 16? PACKING fraction, 2 Pair formation, 58, 47, 54 — in electric field, 73 — mean free path for, 4-9 Paneth, 64 Parent -daughter activity, 25 Parity in beta decay, 61 — gamma decay, 96-9 --compound nucleus, 149-52 Partial wave theory, 117-20, 194-5 Pauli, 157 — principle ; proton-proton scattering, 125' — saturation of nuclear forces, 112 Penetration of nucleus ill internal conversion, 104 Periodic shell structure, 9 Persistence of velocity, 186-8 Photodis integration of deuteron, 175 Photoelectric absorption, J8 Photonucler reactions, 175 Physical Constants, 240 -fT -meson, 131 , 22ia (pion) Piles, chain-reacting theory by Fermi, 208-13 — neutron yield, 180-1 — thermal column, 193-4 Planck radiation law, 94 Plane wave in polar eigenfunctiona , 172 Polar vectors, 99 Polarization of Neutrons, 204-07 Polynomials, Legendre, 15 ponieranchuk, 224- Positron, 48, 5^ — emission, 70-72 Powell, 151 Poynting vector, 89 Primakof, 137 Primary cosmic radiation, 215 — charge of, 233 Protons in cosmic rays, 215, 2.2Z — proton forces, 123-28 — potential, 128 — scattering results, 128 QUADRUPOLE Moment, 15, 21 V, 89-106 RADUTION, Ch. —length, 47 Radiative capture, n by M, 171 Radioactivity, 17 — geological aspects, 19 — biological effect j 18 Ra-Bs source, 179, 191 Radius of nucleus, 6^ Range of oc's, electrons, Jl-2 — of .cosmic ray particles , 222 Rarita, 12J Kasetti, 257, T 101 Reactions; 6* -* \A ' — e. To Be. 1 +■ H 1 -* Li 11 j- Hi*, H7 C " ■* G" * £+ 10 + D — » Me -<- n- ov -* M J + h (T, -n) reaciio-M, I7S ■J 3 - U -*■ H i ■>- /i ,70 H 3 1 H x -» He* 4- N +■ 17. 8 tfev In («, T) resonance, 149 7 7 Li -i- p — * Be -i- ft IFi, l?2 — * Li +■ f> IS"1, [S"X -s 2IU 180. Li e + a -* a« 152 Mm. — > he +■ a , 7lJ {j\t<) 179 5*i — $> Te. f S A" - £f% (80 86 r Silver (*,?-") re;., [47 Recoil experiment, &4 Rectangular barrier, 55 References, 237 Resonance, nuclear, l45 , theory, 152-157 — — , experimental data, 157 - 59 — absorption of dipole radiation, 100 p -Meson, 131 Richtmeyer, 4l Roentgen arid rep, 18 Rosenfeld, L. , 237 Rossi, 36, 49, 54, 2l6, 222 Rutherford, E. , 34, 54 SATURATION of nuclear forces, 111-2 Scattering angle for electrons, 37 — Gompton, 40-2 — cosmic ray electrons, 55 —Coulomb, 34-6, 125-7 —of neutrons, 181 -5, I87, 194, 195 in crystals, 196-205 — partial wave theory, 117-20 — Thomson, 40 Scattering cross section, 118-20 — low-energy, 119-20 — high-energy, 121-2 Scattering length, Iy4-20I Schiff, 237 Schein, ^l^, > 2lS, 2Z2, 233 847 A SS^— ■ Sclwinger, 123, 199 W-igner elements, 83 | Secondary cosmic radiation, 217, 22J Width, T , decay of compound nucleus, 1^ cosmic rays, 217, 98 Secular equilibrium, 17 Segre chart, 1 Segre and helmholz, &9 Selection rules, 96-100 — beta decay, 60 — Garaow-Teller, 81-2 Semi-empirical atomic mass, 6 Shadow effect, 2J2 Shell structure of nuclei, 9, Sherwin, B4 Showers, 49 , 21&-2I3 Simpson, J. A., Jr. 211 Snyder, 1J1 Soft component of 221, 22? Spectra, band, 11 — hyperfine, 10 Spherical harmonics, 97 Spin, dipole radiation. — eigenf unctions, 123~5 —flip, 1?6~8 — inherent, 9-10 —multiplicity, 142, 1% — nuclear, 74 — operator, 173 — see also Angular Momentum Spontaneous emission, 89-94 — of two Quanta. 105 ■ Stars, 1J1, 162, 175, 2 17 State function, molecular, 12 Statistics, 12 — of nuclei, 73 Stem-Geriach, 12 Stormer, 226 Stratton, J .n. , 44 Sun's magnetic field, 215 Symmetry and parity, 15° Synchro- cyclotron, 24 rv, ry . 154, 15a Williams, E.J., 36 X-radiation, 101 YUKAWA, 131, 134, 157- 167 ZEEMAN effect in Solar spectrum, 21 5 T AWT ALUM, y-ansorption res., 175 Teller, 175, 199, '33 Thomas-Fermi atom model, 57 Thomson cross section, 40 Thermal column, ] 9S-4 Thermal neutrona, 191^4, 20 5 Threshold , photodisintegration, 4 — reverse, 5 for nuclear reactions. l4l Tiomno and Wheeler, 237 Two-quantum emission, 105 UNCERTAINTY principle, 148, 155, 13& VALLARTA, 232 Virtual state of deuteron, 120 WENTZEL, 137 WK3 method, 62 Wheeler, 166, J33 248